The Security guard at the hospital, second floor

I was doing the mission where you need to return a werewolf blood vial to the prince, and the guard spots me and says I need to leave, I pay him a hundred bucks and he lets me continue, so far so good.But then, when I remember I have to get to the CS room, I use quicken the blood on him to make him sleep and get a little blood for myself, and he dowsn't fall asleep, instead he starts shooting at me, so I decide to drain him dry and killhim.

I'm not sure about quicken the blood right now. But I think it does not trance the victims. In any case, the upstairs level is combat area. That means feeding, no matter how, doesn't trance anybody. And the guard is a combatant. So as soon as he starts fighting, killing him doesn't cost humanity.